The drive for wireless communications is to allow for greater levels of roaming and allow seamless roaming. Myriad issues, such as handoff between providers, authentication, communication system capabilities and limitations, become increasingly important when roaming, particularly when global roaming is contemplated.
When a mobile node (MN) (also commonly referred to as a mobile station, a subscriber, a user, a terminal, a User Equipment (UE), and the like) moves from an area covered by one network and enters another area covered by another network the call preferably is transferred to the second network without dropping the connection or losing packets. In cellular telecommunications, the term handover or handoff refers to the process of transferring an ongoing call or data session from one channel connected to the core network to another. This function can be referred to as handover with fast mobility.
The term handover or handoff may also apply to when a MN changes from one channel connected to the core network via a first communications controller (also commonly referred to as a base station, a controller, a base terminal station, a NodeB, an enhanced NodeB, and the like) to a second communications controller. Similarly, when a MN is powered on in a new location served by a different network than an immediately preceding network used by the MN, the wireless communications network must recognize the change in location of the MN and direct to the new network the information destined to the MN. This can be referred to as handover with slow mobility.
As more different types of access networks become available, a goal of equipment manufacturers has been to produce a single MN that is capable of operating in multiple access interfaces. These MNs may commonly be referred to as multi-mode MNs, multi-mode phones, global phones, and the like. In order to support multiple access networks, these MNs may have multiple transmit radios to allow for simultaneous access to more than one access network.
Existing methods to perform handover are primarily dual-radio handovers. Dual-radio handover generally requires high peak power consumption capability and sharp signal filtering in the MN due to the use of two or more radios.